Atsutane Ohta

Cooperative effects of exercise training and genistein administration on bone mass in ovariectomized mice.

We reported that genistein, a soybean isoflavone, prevents bone loss caused by estrogen deficiency, without undesirable effects on the uterus. In this study, we examined cooperative effects of genistein administration and running exercise on bone mass in ovariectomized (OVX) mice. Female mice aged 7 weeks were either sham‐operated or OVX and divided into six groups: (1) sham; (2) OVX; (3) OVX, treated with genistein at a submaximal dose (0.4 mg/day) subcutaneously (G); (4) OVX, exercised on a treadmill daily for 30 minutes/day at 12 m/minute on a 10° uphill slope (Ex); (5) OVX, given genistein and exercised (ExG); and (6) OVX, treated with 17β‐estradiol (0.03 μg/day) in the same manner as genistein (E2). Four weeks after intervention, bone mass was estimated by dual‐energy X‐ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Bone mineral density (BMD) of the whole femur measured by DXA was higher in both the G and the Ex groups than in the OVX group. Furthermore, BMD in the ExG group was significantly higher than that in the groups receiving either intervention alone. Bone area in distal region of the femur was significantly higher in Ex and ExG groups as compared with those in the OVX and G groups. pQCT analysis showed that the cross‐sectional areas (CSAs) and periosteum perimeter at midshaft of the femur did not differ in the sham and OVX groups but were significantly higher in Ex and ExG groups. Histomorphometric analysis showed that bone formation rate/bone surface (BFR/BS) was significantly higher in both Ex and ExG groups as compared with that in non‐exercised groups. The bone volume (BV/TV) in the distal femoral cancellous bone was lower in the OVX than that in the sham group, and it was restored completely in the ExG group, as in the E2 group. Thickness of the trabecular bone (Tb.Th) was higher in Ex and ExG groups than that in the OVX and G groups. These results indicate that the combined intervention of moderate exercise and the submaximal dose of genistein administration show a cooperative effect in preventing bone loss in OVX mice.

Comparison of the nutritional effects of fructo-oligosaccharides of different sugar chain length in rats

Abstract The influence of fructo-oligosaccharides of different sugar chain length on growth, nitrogen balance, and mineral balance was examined in rats fed diets containing either sucrose, 1-kestose, nystose, or a mixture of these at 50 or 100 g/kg of diet. Rats were fed the experimental diets for six weeks, and nitrogen balance and mineral (Ca and Mg) balance were examined after the second and fourth week. Food intake and body weight gain did not differ significantly among the groups. Each fructo-oligosaccharide fed was found to increase Ca and Mg absorption dose-dependently during the first balance study period and the degrees of increase in Ca and Mg absorption were similar with each fructo-oligosaccharide fed regardless of the level present in the experimental diet. Also, each of the fructo-oligosaccharides was found to increase fecal excretion of nitrogen, but there was no clear dose-dependence and the extent of increase in fecal excretion of nitrogen was similar for each fructo-oligosaccharide fed. In conclusion, our findings demonstrate that ingestion of fructo-oligosaccharides leads to increases in Ca and Mg absorption and an increase in fecal excretion of nitrogen, however, differences in sugar chain length do not influence their nutritional effects considerably in rats.

Prevention of coprophagy modifies magnesium absorption in rats fed with fructo-oligosaccharides

We developed a new type of anal cup for prevention of coprophagy and determined whether the absorption of Ca and Mg and the stimulatory effects of feeding fructo-oligosaccharides (FO) on the absorption of Ca and Mg were altered by prevention of coprophagy in rats. Rats were fed on a FO-free diet or a diet containing 50 g FO/kg for 2 weeks with or without prevention of coprophagy. FO-feeding increased the apparent absorptive ratio of Ca and Mg in rats with or without prevention of coprophagy. However, in the FO-fed groups the absorptive ratio of Mg in rats with prevention of coprophagy was higher than in rats without prevention of coprophagy. The Ca content of the femur was higher in rats fed on the FO-diet than in rats fed on the FO-free diet both with and without coprophagy. In conclusion, FO-feeding increased the absorption of Ca and Mg in rats both with and without coprophagy. Moreover, prevention of coprophagy enhanced the absorption of Mg in rats fed with FO. Coprophagy has to be considered when the effects of luminal fermentation or mineral absorption are examined in rats.

Fructooligosaccharides stimulate the absorption of magnesium from the hindgut in rats

We investigated the effects of feeding fructooligosaccharides (FO) on the absorption of Mg from the hindgut in cecal-cannulated rats in vivo. Male rats, four wks old male rats, were divided into four groups. Rats in two groups were fed Mg-containing diet and other two groups were fed Mg-free diet with cecal infusion of Mg. Rats of both groups were fed FO-free or FO-containing diet, respectively. The absorptive ratio of Mg administrated into the cecum was similar to that of Mg fed orally in rats fed FO-free and FO-containing diet, respectively. FO-feeding significantly increased the apparent absorption of Mg in both rats fed Mg orally and rats with Mg infused into the cecum. Moreover, the extent of the increase in the absorption of Mg by infusion into the cecum and by oral feeding was the same. In a separate experiment, we observed that only the rats fed Mg-free diet exhibited auricular and facial peripheral hyperemia and hemorrhage. However such symptoms were not observed in the rats with Mg infused into the cecum. In conclusion, these results indicate that FO-feeding stimulates absorption of Mg in the hindgut mainly.

Dietary heme iron does not prevent postgastrectomy anemia but fructooligosaccharides improve bioavailability of heme iron in rats.

Gastrectomized rats exhibit iron deficiency anemia. We observed the effects of dietary heme-iron and short chain frucooligosaccharides (Sc-FOS) in relation to prevention of postgastrectomy anemia in rats. Twelve laparotomized (sham-operated) rats were fed iron-citrate (control) as iron source diet without or with Sc-FOS (75 g/kg of diet) and twenty four totally gastrectomized (Bilroth II) rats, were fed a iron-citrate (control) or heme-iron (heme) as iron source diet without or with Sc-FOS (75 g/kg of diet) for 4 weeks. All rats received an intramuscular injection of vitamin B-12 every two weeks. Tail blood was collected every other week for determination of hematocrit and hemoglobin concentration. At the end of the experiment, the rats were killed and whole blood was collected. The total gastrectomy induced the postgastrectomy anemia. Dietary Sc-FOS increase iron absorption and thereby prevented completely this anemia in gastrectomized rats fed the control diet but this effect of Sc-FOS in rats fed heme diet was not complete. Dietary heme iron could not prevent postgastrectomy anemia itself, but fructooligosaccharides improve bioavailability of not only non-heme iron such as iron-citrate, but also heme-iron in rats.

Dietary short-chain fructooligosaccharides increase calbindin-D9k levels only in the large intestine in rats independent of dietary calcium deficiency or serum 1,25 dihydroxy vitamin D levels.

Dietary short-chain fructooligosaccharides (Sc-FOS) increase mucosal calbindin-D9k (CaBP) levels in the large intestine whereas levels in the small intestine are decreased in rats. In the present study, we investigated the mechanism by which Sc-FOS induce this increase in CaBP in the large intestine by measuring intestinal CaBP levels in rats fed normal and calcium-deficient diets. Dietary groups included a calcium-containing (0.5%) diet with or without Sc-FOS (100 g/kg diet) and a calcium-deficient (abt. 0.01%) diet with or without Sc-FOS (100 g/kg diet). The rats were fed these diets for 10 days following which they were killed and the intestine removed for collection of the entire mucosa which was divided into four segments, i.e., proximal and distal segments of the small intestine, the cecum and the colorectum. Mucosal CaBP and plasma calcium (Ca), 1,25-dihydroxycholecalciferol (1,25(OH)2D3), 25-hydroxycholecalciferol (25(OH)D3), parathyroid hormone (PTH) and calcitonin levels were measured. Feeding of calcium deficient diet resulted in an increase in CaBP levels in the small intestine, but did not influence levels in the large intestine. Moreover, a significant positive correlation between plasma 1,25(OH)2D3 and CaBP levels in the case of both small intestinal segments (proximal, r = 0.77012, p < 0.00007; distal, r = 0.75056, p < 0.00014) was observed, but not in the case of the large intestinal segments. Sc-FOS increased CaBP levels in the large intestine. These results suggest that the large intestinal CaBP levels do not change in response to dietary calcium conditions and are not regulated by circulating 1,25(OH)2D3 indicating that the effect of Sc-FOS on CaBP levels in the large intestine is independent of the action of 1,25(OH)2D3.

The effect of short chain fructooligosaccharides in promoting recovery from post-gastrectomy anemia is stronger than that of inulin

The purpose of this study was to compare the effects of two indigestible carbohydrates, short chain fructooligosaccharides (Sc-FOS) and inulin, on post-gastrectomy anemia. Four-week-old rats were subjected to gastrectomy or laparotomy (sham operation) and 6 weeks after surgery the animals were divided into one sham group and three gastrectomized groups. The gastrectomized rats were fed experimental diets containing either sucrose (control), 7.5% Sc-FOS or inulin for 6 weeks. The sham operated rats were fed the control diet. During the experimental feeding period, blood was collected by tail vein puncture every week for determination of hemoglobin concentration (Hb) and hematocrit (Ht). The Hb and Ht values obtained for rats fed the Sc-FOS-containing diet were significantly higher than those for gastrectomized rats fed the control diet or the inulin-containing diet. In conclusion, the present study demonstrates that the effect of Sc-FOS in promoting recovery from post-gastrectomy anemia is stronger than that of inulin in rats.

Synergistic effect of isoflavone glycosides and fructooligosaccharides on postgastrectomy osteopenia in rats

Fructooligosaccharides stimulate the growth of Bifidobacteria, which cleave isoflavone glycosides to yield corresponding aglycones, and convert metabolites by enhancing enterohepatic recirculation of isoflavones in rats. In the present study, we determined the synergistic effect of dietary isoflavone glycosides and fructooligosaccharides on postgastrectomy osteopenia in rats. Nine-week-old male Sprague-Dawley rats were gastrectomized (n = 20) or sham operated, (control, n = 5) and then randomly assigned to 5 diet groups: sham-a purified diet control, gastrectomized-control, gastrectomized-isoflavone (0.2% isoflavone glycosides), gastrectomized-fructooligosaccharides (7.5% fructooligosaccharides), and isoflavone and fructooligosaccharides (0.2% isoflavone glycosides + 7.5% fructooligosaccharides). After 6 weeks, the rats were killed and biological samples were collected. In gastrectomized rats, fructooligosaccharides prevented femoral bone fragility, but isoflavone without fructooligosaccharides did not inhibit postgastrectomy osteopenia. Isoflavone and fructooligosaccharides exhibited a synergistic in the distal metaphyseal trabecular bone, indicated by peripheral quantitative computed tomography. Moreover, fructooligosaccharides increased calcium absorption and equol production from daidzein in gastrectomized rats. These results indicate that isoflavone alone did not inhibit postgastrectomy osteopenia, but the combination of isoflavone and fructooligosaccharides improved the inhibition of trabecular bone loss by increasing calcium absorption and equol production through fructooligosaccharides supplementation.

The frequency of magnesium consumption directly influences its serum concentration and the amount of elutable bone magnesium in rats

We investigated the influence of Mg feeding frequency on the variation in serum Mg concentration and tissue Mg levels in Mg-deficient rats. Sprague-Dawley rats, which had been fed a Mg-deficient diet for 14 d, were divided into 3 groups that were kept on 3 diets differing in their Mg content. The rats were fed 0.5-fold (Mg250 group), 1-fold (Mg500 group), or 1.5-fold (Mg750 group) the amounts of recommended Mg in their standard AIN-93G diet (Mg: 478 mg/kg diet) during the recovery period (12 d). The Mg500 and Mg750 groups were intermittently fed (Mg500, every 2 d; Mg750, every 3 d) so that their total intake of Mg during the recovery period could equal the Mg intake of the Mg250 group. The serum Mg concentrations increased in the 3 groups after feeding with a Mg-containing diet. However, serum Mg levels were only maintained within the normal range in the Mg250 group. After feeding on the Mg-deficient diet, in the intermittently fed groups, serum Mg concentrations decreased. Urinary Mg excretion was higher and Mg retention was lower in the Mg500 and Mg750 groups than in the Mg250 group. Moreover, bone Mg, especially elutable bone Mg, was lower in the Mg500 and Mg750 groups than in the Mg250 group. The elutable fraction of bone Mg correlated to the coefficient of variation of serum Mg concentration. In conclusion, for the maintenance of serum Mg concentration, it is important to increase the amount of elutable bone Mg by frequent Mg consumption.